elf: Refuse to dlopen PIE objects [BZ #24323]

[thirdparty/glibc.git] / elf / dl-tunables.h

diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
index 033781856ac955a6ff20890a972fae74ac76b751..58b3b768432c661065995f5828f88a86f1d1a650 100644 (file)
--- a/elf/dl-tunables.h
+++ b/elf/dl-tunables.h
@@ -1,7 +1,7 @@
 /* The tunable framework.  See the README to know how to use the tunable in
    a glibc module.
 
-   Copyright (C) 2016 Free Software Foundation, Inc.
+   Copyright (C) 2016-2019 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -24,7 +24,7 @@
 #if !HAVE_TUNABLES
 static inline void
 __always_inline
-__tunables_init (char **unused __attribute_unused)
+__tunables_init (char **unused __attribute__ ((unused)))
 {
   /* This is optimized out if tunables are not enabled.  */
 }
@@ -39,13 +39,18 @@ struct _tunable
   const char *name;                    /* Internal name of the tunable.  */
   tunable_type_t type;                 /* Data type of the tunable.  */
   tunable_val_t val;                   /* The value.  */
-  const char *strval;                  /* The string containing the value,
-                                          points into envp.  */
-  bool is_secure;                      /* Whether the tunable must be read
-                                          even for setuid binaries.  Note that
-                                          even if the tunable is read, it may
-                                          not get used by the target module if
-                                          the value is considered unsafe.  */
+  bool initialized;                    /* Flag to indicate that the tunable is
+                                          initialized.  */
+  tunable_seclevel_t security_level;   /* Specify the security level for the
+                                          tunable with respect to AT_SECURE
+                                          programs.  See description of
+                                          tunable_seclevel_t to see a
+                                          description of the values.
+
+                                          Note that even if the tunable is
+                                          read, it may not get used by the
+                                          target module if the value is
+                                          considered unsafe.  */
   /* Compatibility elements.  */
   const char *env_alias;               /* The compatibility environment
                                           variable name.  */
@@ -56,37 +61,71 @@ typedef struct _tunable tunable_t;
 /* Full name for a tunable is top_ns.tunable_ns.id.  */
 # define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id
 
-# define TUNABLE_ENUM_NAME(top,ns,id) TUNABLE_ENUM_NAME1 (top,ns,id)
-# define TUNABLE_ENUM_NAME1(top,ns,id) top ## _ ## ns ## _ ## id
+# define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id)
+# define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id
 
 # include "dl-tunable-list.h"
 
 extern void __tunables_init (char **);
-extern void __tunable_set_val (tunable_id_t, void *, tunable_callback_t);
+extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
+extern void __tunable_set_val (tunable_id_t, void *);
+rtld_hidden_proto (__tunables_init)
+rtld_hidden_proto (__tunable_get_val)
+
+/* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
+   TUNABLE_NAMESPACE are defined.  This is useful shorthand to get and set
+   tunables within a module.  */
+#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
+# define TUNABLE_GET(__id, __type, __cb) \
+  TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
+# define TUNABLE_SET(__id, __type, __val) \
+  TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __val)
+#else
+# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
+  TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
+# define TUNABLE_SET(__top, __ns, __id, __type, __val) \
+  TUNABLE_SET_FULL (__top, __ns, __id, __type, __val)
+#endif
 
-/* Check if the tunable has been set to a non-default value and if it is, copy
-   it over into __VAL.  */
-# define TUNABLE_SET_VAL(__id,__val) \
+/* Get and return a tunable value.  If the tunable was set externally and __CB
+   is defined then call __CB before returning the value.  */
+# define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \
 ({                                                                           \
-  __tunable_set_val                                                          \
-   (TUNABLE_ENUM_NAME (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id), (__val),      \
-    NULL);                                                                   \
+  tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id);                   \
+  __type ret;                                                                \
+  __tunable_get_val (id, &ret, __cb);                                        \
+  ret;                                                                       \
 })
 
-/* Same as TUNABLE_SET_VAL, but also call the callback function __CB.  */
-# define TUNABLE_SET_VAL_WITH_CALLBACK(__id,__val,__cb) \
+/* Set a tunable value.  */
+# define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \
 ({                                                                           \
-  __tunable_set_val                                                          \
-   (TUNABLE_ENUM_NAME (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id), (__val),      \
-    DL_TUNABLE_CALLBACK (__cb));                                             \
+  __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id),                  \
+                       & (__type) {__val});                                  \
 })
 
 /* Namespace sanity for callback functions.  Use this macro to keep the
    namespace of the modules clean.  */
-# define DL_TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
+# define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
 
 # define TUNABLES_FRONTEND_valstring 1
 /* The default value for TUNABLES_FRONTEND.  */
 # define TUNABLES_FRONTEND_yes TUNABLES_FRONTEND_valstring
+
+/* Compare two name strings, bounded by the name hardcoded in glibc.  */
+static __always_inline bool
+tunable_is_name (const char *orig, const char *envname)
+{
+  for (;*orig != '\0' && *envname != '\0'; envname++, orig++)
+    if (*orig != *envname)
+      break;
+
+  /* The ENVNAME is immediately followed by a value.  */
+  if (*orig == '\0' && *envname == '=')
+    return true;
+  else
+    return false;
+}
+
 #endif
 #endif